REAL-TIME SPECTROSCOPIC ELLIPSOMETRY STUDIES OF DIAMOND FILM GROWTH BY MICROWAVE PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

We have applied real-time spectroscopic ellipsometry to monitor the gr owth of highly uniform, nanocrystalline diamond films by microwave pla sma-enhanced chemical vapour deposition. In this study, a unique multi channel instrument is employed to collect full ellipsometric spectra f rom 1.5 to 4.0 eV. Here we focus on two capabilities. First, we will d escribe a method to calibrate the true temperature of the top 200 angs trom of the Si substrate under diamond growth conditions. Second, we d escribe the full microstructural evolution of the diamond films. The p arameters derived include the time evolution of the void and optically absorbing, non-diamond (sp2) carbon volume fractions in the film. In addition, the nuclei, bulk and surface roughness layer thicknesses dur ing the nucleation, coalescence and bulk growth regimes are determined . These results reveal reproducible and remarkably internally consiste nt behaviour that provides new insights into the growth mechanisms for nanocrystalline diamond. We find that in the coalescence process, a l arge volume fraction of sp2 carbon is trapped in the grain boundaries under all conditions of growth. After coalescence is complete, further generation of sp2 carbon is impeded under optimum conditions.